Pulse analyzer



June 28, 1960 1 A 2,943,262

PULSE ANALYZER Filed Oct. 28; 1957 2 Sheets-Sheet 1 22 76 f RN (0 AT" 2040 S I8 11 IO ea x I 73%, F u 64-. 1o

R\ 4| u h 42 TRIGGER DELAY Y BI-STABLE mwunen u.v. u.v. 8+ 72 Y I l 2HIGH TRIGGER Bl-STABLE I rnsouzncv u.v. OSCILLATOR FLIP-FLOP mvznrmeAMPLIFIER no H2 H4 use. BIAS v vb v v vvv 10s I408 i INVENTOR.

JOHN D. BALL ATTORNEY.

June 28, 1960 Filed Oct. 28. 1957 PULSE TO BE ANALYZED TRIGGER PULSEDELAY M. V. PULSE HOLD OFF GATE PULSE RESET PULSE STRETCHED PULSE HIGHFREQ. OSCILLATOR TRIGGER PULSE FLIP- FLOP STAIR STEP RESET PULSE J. D.BALL 2,943,262

PULSE ANALYZER 2 Sheets-Sheet 2 T/ FIG. 2.

P 2% L l :x CHARGE TIME UTPUT T0 sroruee CIRCUIT 1 I38 FROM U '40HOLDING cmcun' FROM sum-s12? F GENERATOR INVENTOR.

JOHN 0. BALL,

AT TOR N.E Y.

United States PULSE ANALYZER John D. Ball, Houston, Tex., assignor, bymesne assignments, to Jersey Production Research Company, Tulsa, Okla.,a corporation of Delaware Filed Oct. 28, 1957, Ser- No. 692,948

7 Claims. (Cl. 328-115) This invention relates to pulse heightanalyzers. More voltage level above a predetermined level. The bias ofeach electronic tube is different from the bias of the tubes in theother channels. All of the pulses which have a voltage level above thepredetermined level in aparticular channel are registered in a registerincluded in said channel. The number of pulses between two, voltagelevels is determined by subtracting the number of pulses 7 above onevoltage level from the number of Pulses above the next lower voltagelevel.

The foregoing type of analyzer has the disadvantages 7 conditionpreparatory to the receipt of the nextpulse to r be controlled byreference to the in which: V V v Fig. 1 is a diagram partially in blockform and par that a plurality ofchannels are necessary, resulting in anexcessive number of electrical components when alarge variety of pulsesare being measured simultaneously and the number of pulses in aparticular voltage level are not indicated directly, the subtractingprocedure being necessary to determine the number of pulses in theparticular voltage level. 1 v I A second type of analyzer currently usedincludes a selector for varying the bias upon the channel.' Here again,the number of pulses registered consists only of those pulses above apredetermined voltagelevel. The

number of pulses within a particular voltage level is not registereddirectly.

A pulse height analyzer which utilizes only one channel for measuringthe number of pulses of aplurality of pulses which are in eachparticular voltage level is highly desirable. Such a pulse heightanalyzer is even more desirable and advantageous it the number of pulseswithin each voltage level is indicated directly.

It is an object, therefore, of this invention to provide an analyzerwhich requires only one channel for the measurement of a plurality ofpulses of different voltage levels.

It is a further object of this invention to provide an analyzer whichindicates the number of pulses in each voltage level directly.

Briefly described, this invention includes a holding circuit, acomparing circuit, a storage circuit, and a stair-' step voltagegenerating circuit; The holding circuit receives each input pulse andmaintains an output voltage level for a time sufliciently long todetermine the voltage level of the input pulse. The holding circuitoutput voltage is fed to the comparing circuit. A stair-step voltagefrom thestair-step generating circuit is also fed to the comparingcircuit. When the stair-step voltage level is at a particular levelrepresentative of the voltage level of the input pulse, the comparingcircuit produces a signal which is fed to the storage circuit. Thestorage circuit includes a plurality of indicators, which may be digitalor analogue, with each indicator being controlled by a gate whichremains open only for a period of time sulficient to indicate thepresence of a particular voltage level which is different from thevoltage level-at which any of the other gates are maintained open.

The gates may be controlled by the same stair-step volt-age which is fedto the comparing circuit so. that each gate is open only at the samevoltage level as the stairstep voltage level fed to the comparingcircuit. By this means only the pulses which are at a particular voltagelevel are registered by'a particular indicaton. After each pulse heightis indicated, a resetting signal is fed to they holding circuit to resetthe holding circuit to its initial be measured. The resetting-signal mayby the stair-step voltage generator.

A better understanding of this invention may behad following,description 'and drawings tially schematic illustrating one embodimentof the in vention;

v Fig. 2 is a graph useful in explaining the operation of the holdingcircuit of Fig. 1;

Fig. 3 is a graph useful'inexplaining the operation of the stair-stepvoltage generator of'Fig. l; g V Fig. 4 is an electricalschematicdiagram illustrating a portion of the storage circuitshownin 1;and :1 Fig. 5 is anelectrical schematicdiagram showing a second type ofcomparing circuit which may; be used in."

place' oi the comparing circuit shown in Figy-l.

' Referring to Fig. 1-, the pulses" to be measuredare from" terminal 10through resistor"12 to theplates of diode tubes 14 and 16. Diode 14 isof the high backresistance type and serves as a cha'rgediode; Since the,7 pulse is of positive polarity, the charge tube 14is made conductiveso. that the grid to-cathode'voltage of tr-iode tube 18 is made morepositive. This decreases the .volt- 'age'at the plateZt) of triode 18and acharge is built up in capacitor 22. Diode 36 remains non-conductiveuntil anegativ pulseis appliedtothecathode' of diodef3 6.

The pulsesto be measured do not risedirectly from a zero voltage '[01'&higher voltage level; the rise occurs over a finite time. Therefore, itis necessary to maintain charge diode 14 in operation for a period oftime sufiicient 'to permit the rise time to occur. This is accomplishedby, diode 16 which isheld non-conductive until a negative voltage isapplied to its cathode 23. The appliv cation of the negative voltage isdelayed for alperiod of time suflicient to permit a maximum rise time ofthe pulses to occur and the capacitor 22 to become fully charged. ,Diode16 may be called a hold off gate and the negative pulse applied to itscathode may be called the hold olf pulse. V 7

The delay in application of the hold. off pulse to cathode. 23of diode16 is accomplished by means of trigger ampli" fier 24, delaymultivibrator 26, and bi-stable multivibrator 28.; The triggeramplifier, delay multivibrator, and bistable multivibrator areof'conventional design; The

function of these circuits maybe better understood by reference to Fig.2. The pulse to be analyzed having a pulse height h is fed to. thetrigger amplifier 24 which emits a trigger pulse 30. After a fixed delayequalto the maximum rise time of the pulses to be analyzed, the delaymultivibrator emits a pulse 31 which is fed to bi-stable multivibrator28. Bi-stable multivibrator 28 is changed 'to its lower voltage stable'state by the application of" pulse 31. The output of bi-stablemultivibrator 28 is connectedto cathode 23. Hence, the cathode 23 ofdiode I 2,943,262] ramm s June 2a, "1960} 16 is made more negative bythe application of trigger pulse 31 to multivibrator 28.

The pulse from multivibrator 28 causes diode 16 to become conductive,thus making plate 32 less positive as well as plate 34 of diode 1 4: sothat diode 14 becomes non-conductive, preventing a second pulse frombeing applied until the hold oif is released. Since there is no closedcircuit to discharge capacitor 22, the grid to cathode voltage of triode18 remains the same, thus maintaining the output voltage of the holdingcircuit the same until the capacitor 22 is discharged. The outputvoltage from the plate of triode 18 is kept for a period of timesufficient to permit the measuremen t of the height of the holdingcircuit output pulse in a manner to be subsequently described. 7 V V IAfter the output pulse has been measured and registered, the capacitor22 is discharged by means of a negative pulse fedto the cathode ofdischarge diode 36. The holding circuit is then ready to measure thepulse height of the next pulse input.

The plate voltage of triode 18 is connected to a comparing circuitincluding diodes 40 and 42, and triodes 44 and 46. The plate voltagefrdm triode 18 is compared in the comparing circuit with a voltage inthe plate circuit of a triode tube 48 comprising part of astair-stepgeneratr,

ing circuit to be subsequently described.

The stairstep generating circuit includes a high-frequency oscillator50, a trigger amplifier 52, and a bi -stable multivibrator flipflopcircuit 54. Trigger amplifier 52 emitsa trigger pulse each timethesignal from the oscillator 50 crosses the zero linefrom one voltagepolarity to another voltage polarity, a positive trigger pulse beingemitted as the oscillating'signal goes from positive voltage to negativevoltage, anda negative trigger pulse being emitted when the oscillatingsignal goes from a negative polarity to a positive polarity. This isclearly illustrated in the graphical representation of Fig. 3. Thebi-st'able flip-flop circuit 54 is changed from'one, stable stateto theother stable state uponreceipt of a negative pulse from When theflip-flop voltage swings to a more positive voltage, the charge diode 56becomes conductive. Triode 48 also conducts and a negativecharge withrespect to plate 58 is put on plate 62 of a capacitor 60. Upon thenegative swing of flip-flop circuit 54, the charge diode becomesnon-conductive.

Diode 65 is normally non-conductive;and isof the type that will notbecome conductive until'a certain predetermined positive charge is puton plate 58of capacitor 60. Hence, the charges remain on capacitor 60until diode 65 becomes conductive. On the next positive upswing of theflip-flop voltage, plate 58 becomes more positively charged and plate 62becomes charged more negatively. Therefore, the plate voltage of-triode48 decreases in incremental voltage steps. After a predetermined numberof stair-stepping voltages, the charge on plate 58 becomestriggeramplifier 52.

sufiiciently positive to cause discharge diode 65 to conduct. When diode65 begins to conduct, the capacitor 60 is discharged and returned toitsinitial state to begin the cycle over again.

The discharge throughdischarge diode 65'is conducted through line 69 andinverting amplifier 67 tothe" cathode of diode 36 and to the bi-stablemultivibrator 28. The

Plate 68 of 4 cent levels of the stair-step voltage from the voltagegenerating source.

The plate voltage from triode 18 of the holding circuit is fed to thecathodes of diodes 46 and 42 of the comparing circuit through resistors76 and 78, respectively. Resistors 76 and 78 are muchgreater inmagnitude than resistors 64, 70, 74, and 66 in the plate circuits ofdiodes 40 and 42. I g

I'f junction X is more positive than the holding circuit output, pulsediode 4% will conduct, making junction 0 positive. If the holdingcircuit output pulse is sufficiently negative to make diode 42 conductalso, then junction R will also be positive Triodes 44 and 46 with theirresistors 80, 82, and 84 constitute a differential amplifier which willhave no output if both inputs have the same signal applied. Therefore,an output from the plate circuit of triode 46 is obtained only when theholding circuit output voltage causes diode 46 to conduct but not'diode42. I y 7 V Frdi'ii the foregoing explanation it is seen that if theinitial voltage ofthe stair-step voltage is zero and a negativepfilsei'sa plied to the cathodes of diodes 4 0 and 42 from the platecircuit oftriode l8, -bqth diodes" 40 and 42'conduct aiid there is be output trornthe plate circuit of triode 46; Since the stair-step voltage magnitudeincreases in the negative direction, a point will be reached atWhichtl'ie plate 68 of diode 46 becomes negative with respect tojuiictidn' 0. However, since the plae 72 of diode 42 is negativelybiased by a negative bias which is e'qiiil'to an incremental step of thestair-step voltage, diode 40 will conduct before diode 42 begins toconduct. At this point, an oiitpiit pulse will be obtained from theplate of triode 46. As the stair-step voltage continues to'increa'se inmagnitude in the negative direction, diode 42" conducts no output isobtained from the triode 46; Hence, a single pulse is obtainedfrom theplate circuit of triode 46 when the stair-step voltage reaches 7 a levelrepresentative of the voltage level of the particular pulse whose heightisbeing measured.

j The manner in which the storage circuitop erates is best explained byreference to' Fig. 4 which shows one gate circuit for oiie register.Fig. 4 represents a portion of the storage circuit shown in Fig. l. g VH Each'g'ating'cir'cuit includes a pair of diodes and 192.; The cathodeof diode 100 is positively biased with respect to the plate of diode 192by one step e equivalent to onestep of the stair-step generated volta-geThe plateof di'o de.102 and cathode of 100 are coniie'cted'to thestair-step voltagethrough resistors 108. A ne'gative bias is applied tothe plate of diode 100 and the cathdde'ofTGZ through a resistor 103. Aslong as junction c'is positive with respect to the negative bias, diode102 conducts and no charge is placed on thecapacit or 104. When junctionC is equal in potential' to the negative bias applied to the cathode,diode 102 beconies' non-conductive, and since diode 100 is alsonon-conductive because its cathode is positively biased, the capacitor104 will become charged if a signal is received at that time from thecomparing circuit through resistor 106., The receivedsignal is passed toa register such as a digital recorder 1 20, or in the alternative, ananalog recorder.

The next stair-step after diode 102 becomes non-conductive, thepotential at junction Dff will be equal-to the potential at the plate ofdiode 109, anddiode 100 will become conductive. Thereafter nocharge isplaced on capacitor 164 Hence, a pulse passed tp theregister of thisgating circtiit only if it received when the stairste'p'- generatedvoltage is at" a p ariticular voltage level.,

This voltage level: represent; a'particular voltage level of themeasuredinput piilse from terminal 10 (see QU Rie'sistorstl0 3 land 196are of a much greater magnitu'de than resistors 1118;; in the cathodeand plate circuits of diodes 100 and 102, respectively. Alsorthe'pulse".reset the holding circuit to receive the next pulse.

from the comparing circuit is held to a height (it) less than onestair-step at the C and D junctions.

Referring again to Fig. 1, it is seen that the storage circuit includesa plurality of gating circuits similar to that shown in Fig. 4. However,each gating circuit is negatively biased by a different negative biasapplied by means of a voltage divider, including resistors 110, 112, and114. Since all of the gating circuits are similar to the gating .circuitdescribed and operate in the same manner except for the differentnegative bias applied to each gating circuit, the description of theoperation of the remaining circuits is deemed unnecessary.

As each stair-step voltage is fed through line 116 to the storagecircuit, the gating circuits open sequentially, and each remains openfor one stair-step peirod and then closes. If a singal is received fromthe comparing circuit, it will be registered-in one of the registers 120according to the particular voltage level of the input pulse, the heightof which is being determined. Hence, all of the pulses having aparticular voltage level are directly registered in one of the registers120, and the computational steps currently required in other pulseheight analyzing systems is eliminated.

A second type of comparing circuit which may be sulr stituted for thediodes 40 and 42 and triodes 44 and 46 shown in Fig. 1 is shown in Fig.5. A modified Schmitt trigger circuit is used, including triodes 130 and132. The cathodes of triodes 130 and 132 are connected to a commonresistor 134, which is grounded. The grid of triode 130 receives thesignal from the holding circuit, and the grid of triode 132 receives thestair-step voltage from a stair-step voltage generator through resistor136. The plate voltage from triode 132 is fed to the storage circuitthrough capacitor 138. The application of the negative voltage from theholding circuit to the grid of triode 130 causes the plate of triode 130to swing positively, thus causing the grid of triode 132 to becomepositive due to the charging of capacitor 140. As the magnitude of thestair-step generator voltage increases in the negative direction, thepotential of the grid of tube 132 becomes less and less positive, untilthe voltage trom the stair-step generator is-the same as the voltagefrom the holding circuit to the grid of 130, at which time the grid oftriode 132 becomes negative. At this point, triode 132 ceases to conductand a positive pulse is fed from the plate circuit of triode 132 to thestorage circuit.

To describe the operation of the complete system, refer to Fig. 1.Assume the holding circuit has just been reset and an input pulse hasbeen fed to the holding circuit. A holding circuit output pulse is heldin the circuit for a period of time suificient to permit the measurementof its voltage level. The stair-step voltage is fed to the comparingcircuit and also fed through line 116 to the storage circuit. The gatingcircuits of the storage circuit are opened sequentially in response to aparticular stair-step voltage level. Each gating circuit is held openonly when the stair-step voltage is at the particular voltage level forthe particular gating circuit. The gating circuit then remains closeduntil the same voltage level is again received. When the stair-stepvoltage level is obtained which is representative of the voltage levelof the input pulse, a pulse is fed from the plate of triode 46 in thecomparing circuit and is registered on the register whose gating circuitis open at that time.

After a predetermined number of stair-step voltages,

' which number is chosen so that the maximum magnitude in the negativedirection is greater than the maximum magnitude of the pulses to bemeasured, the reset pulse is fed through diode 65 in the voltagegenerating circuit and inverting amplifier 67 to the bi-stablemultivibrator 28 and the cathode of diode 36 in the holding circuit todischarge the capacitor 22 in the holding circuit and The reset pulsesare always of the same height and durationso that the capacitor 22 isdischarged the same amount at each resetting. The analyzer isno'wieadyto nieas= ure the height of the next incoming pulse throughterminal 10 and the cycle repeated.

From the foregoing, it is seen that the analyzer utilizes only one inputterminal instead of the many input terminals and separate channelshaving a dilferent bias re-.

of the height of the input pulse; means for producing a stair-stepvoltage; a comparing circuit for comparing the holding circuit outputpulse with the stair-step voltage and adapted to produce a signal whenthe stair-step voltage reaches a level representative of thevoltage'level of said input pulse; and means responsive to said signalto indicate the magnitude of said input pulse. 7

2. A pulse height distribution analyzer comprising: a

holding circuit for receiving an input pulse and producing an outputpulse of substantially constant magnitude, said magnitude beingrepresentative of the height of the input.

pulse; astair-step voltage generating circuit adapted to make step-wisevoltage changes from an initial voltage to a final voltage and thenreturn to the initial voltage; a comparing circuit for continuouslycomparing the holding circuit output pulse with the stair-step voltageand adapted to produce a signal when the stairstep voltage reaches alevel representative of the voltage level of said input pulse; meansresponsive to said signal to indicate the magnitude of said input pulse;and means for conducting a resetting pulse to the holding circuit.

3. A pulse height distribution analyzer comprising: a holding circuitfor receiving an input pulse and maintaining an output voltage levelrepresentative of the height of the input pulse for a time sufiicientlylong to determine the voltage level of said input pulse; a comparingcircuit; a storage circuit including a plurality of indicators, one foreach possible voltage level of input pulse; and a stairstep voltagegenerating circuit electrically connected to the holding circuit, thecomparing circuit, and the storage circuit and adapted to feed astair-step voltage to the comparing circuit and storage circuit, and aresetting signal to the holding circuit whereby the height of said pulseis indicated and the holding circuit reset.

4. A pulse height distribution analyzer comprising: a holding circuitfor receiving a pulse and maintaining an output voltage representativeof the height of the input pulse for a time sufiiciently long todetermine the voltage level of said input pulse; a comparing circuit forcomparing the holding circuit output voltage with a stairstep voltageand producing a signal when the stair-step voltage reaches a levelrepresentative of the voltage level of said input pulse; a storagecircuit including a plurality of indicators, each including a gate whichremains open only while receiving a particular voltage different fromthat received by any other gate; and a stair-step voltage generatingcircuit electrically connected to the holding circuit, the comparingcircuit, and the storage circuit and adapted to feed a stair-stepvoltage to the comparing circuit and storage circuit and then aresetting signal to the holding circuit whereby the height of said pulsefor a time sufliciently long to determine the voltage level of saidinput pulse; a comparing circuit for comparing the holding circuitoutput voltage with a stair- Ste'p' voltage aha producing a signal whenthe stair-step voltage reaches a level representative of the voltagelevel of sa'i'dinpiit pulse; a'stomg'e circuit including a plurality ofindi'cators', e'a'ch ihcluding a gate which remains open only Whilereceiving a particular voltage ditfer'ent from that received by anyother gate; a stair-step voltage generating circuit including acapacitor which is charged in steps to provide the stair-step voltage;me ans for conducting said stair-step voltage to the comparing and storage circuits so that the height of said pulse is indicated; and meansresponsive to a predetermined number of stairstep voltage steps fordischarging the capacitor and re setting the holding circuit. p

6. A piil'se hight distribution analyzer comprising: a holding circuitfor receiving each pulse and including a vacuum tube responsive tosaidpulse to produce an output voltage; means for maintaining said outputvoltage at a level representative of the height of said pulse after thepulse has been received; a comparing circuit for compari'ng the holdingcircuit output voltage with a stair-step voltage and producing a signalwhen the stair-step voltage reaches a level representative of thevoltage level of said input pulse; a storagecircuit including aplurality of indicators, each including a gate which remains open onlyWhile receiving a particular voltage different from that received by anyother gate; a stair-step voltage generating circuit including acapacitor which is charged in steps to provide the stair-step voltage;means for conducting said stair-step voltage to the comparing andstorage circuits so that the height of said pulse is indicated; meansresponsive to a predetermined number of stair-step voltage steps fordischarging the capacitor; arid mea'jris for conducting the dischargesignal to the holding c'irciiit tci reset the vacuum tube to itsinitialstate.

7. A pulse height distribution analy'z'er for measuring the heights ofpulses including pulses having a finite rise time comprising: aho'ldingcircuit for receiving an input urse and producing a holding'circuitoutput pulse; a hold off circuit operatin'gytirst, to pefinit the inputpulse to be fed to the holding circuit until the maximum height of theinput pulse is obtained; and, second, to thereafter p'ievent the feedingof a signal to the holding circuit until after the maximum height of theinput pulse is indicaiemmea'ns for producing a stair-step voltage; acomparing circuit for comparing the holding circuit output pulse withthe stair-stepvoltage and adapted to produce a signal When thestair-step voltage reaches a level repre-' sentative of the voltagelevel of said input pulse; and n'ie'ahs responsive to said signal toindicate the magnitude of said input pulse.

References Cited in the file of this patent UNITED STATES PATENTS2,227,952 White DEC. 31, 1940 2,743,359 Sayre Apr. 24, 1956 2,759,998Labinet al Aug. 21, 1956 2,796,314 Bishop et al June 18, 1957

